What are the Different Types of Tree Species?
There are around 100,000 tree species across the world. Although the majority of these species are in a tropical environment, trees can be found throughout almost any region of the world: in fact, trees number 25% of all plant life. The various species of trees can be divided into many different categories, such as forest species, evergreen species or endangered species.
A plant must possess several characteristics in order to be categorized as a species of a tree. Most experts agree that trees are perennial, meaning that they live for at least two years. Trees are also typically a woody plant, and many scientists claim that trees will have a clearly defined trunk with branches.
The earliest tree species that still exist today are tree ferns. These trees can survive in both tropical and subtropical environments. They are often found in rainforests, along with certain regions of Australia and the South Pacific islands.
The are over 100 kinds of tropical tree species, with the Arecaceae, more commonly known as the palm tree, being one of the most well-known. Most palm trees require a low, wet region to thrive, but there are 130 lesser-known palm species that grow outside the tropical regions. Although palm trees have a minimalist appearance, they have been used for many purposes throughout history, from practical resources to spiritual rituals.
The classification "evergreen" means that these trees keep their green leaves all year, never falling into traditional seasonal patterns. Evergreen tree species tend to flourish in even the harshest environments. Pine trees might be found in warm ocean-front settings, but they can also bear through long freezing winters in northern America and Canada. Although pine trees and other evergreens can survive despite drastic temperature fluctuations, they do usually need an acidic soil to grow in.
Deciduous trees are the opposite of the evergreen. These trees have a yearly pattern of color-changing leaves, bare branches, flowering buds, and leafy green life. Deciduous literally means "that which falls off." Leaves might start falling off at the onset of cold weather or as the atmosphere begins to dry up. Some deciduous tree species include birches, oaks or poplars.
Several species of trees have made it to the endangered list. The Bois Dentelle is the rarest tree species alive. There are only two Bois Dentelles still standing, both growing in Mauritius. These trees have bell-shaped flowers with petals resembling lace. Although experts have not decided on a reason for their decline, most do not believe that their endangerment is the result of any human actions.
The article mentions palm trees in the family Aracaceae being trees, but I think that usually goes against the definition of a tree.
Palms are definitely woody, but they aren't wood in the classical sense. Plants in that family are actually monocots like grasses meaning that they can only grow upward and not outward.
I believe one of the additional classifications for a tree is that it has secondary branching. If you look at a true palm tree, all of the leaves come out of a central area. There are not branches.
That is just what I was always taught. I'm curious if others have read and heard the same thing of if I'm alone on this.
@Izzy78 - I would agree that tropical areas contain more than half. I'd say 50,000 is a way low estimate.
I was interested in the Bois Dentelles since I had never heard of that before. The flowers are very pretty. It is too bad there are only two of them left, since trees with nice looking flowers in the wild are very hard to come by.
On a different note, I think it is amazing how fast and slow some trees can grow. I was reading an article recently that was talking about some eucalyptus tree species from the tropics that can grow over 10 feet per year. That seems incredible considering the newly planted trees in my year barely grew 6 inches! On the other hand, the worlds oldest trees, the bristlecone pines, have been alive for thousands of years and are only a couple feet wide.
@TreeMan - As far as the number of evergreens versus deciduous trees goes, I got curious about the same thing. I think it is important to make the distinctions between conifers and deciduous, though. Conifers are just trees that make cones, by definition. Everything else is considered broadleaf trees. Broadleaf trees don't necessarily have to be deciduous, though. I live in the southeastern United States where we have a tree called live oak. It keeps its leave on all year as do many of the tropical tree species.
I looked it up, though, and conifers only represent about 600 species out of the 100,000 that the article mentioned. That is a much smaller percentage than I expected.
I would disagree with the article saying there are 100 tropical tree species. Tropical areas have the vast majority of tree species, so at least 50,000 around the world.
Wow, I didn't have any idea there were that many tree species around. I live in the western part of Canada where it seems like we just have 5 or 6 species of conifers. I always like visiting forests in the east where there is much more variety.
Does anyone have any idea what the ratio of evergreen to deciduous trees is? Considering that the rainforests are mostly if not all deciduous trees, I would have to assume conifers make up a pretty small minority.
The article mentions that tree ferns are the oldest tree species. Are they still around or have they gone extinct?
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